We present our new measurement of the cross-section for charm dimuon production in neutrino–iron interactions based upon the full statistics collected by the NOMAD experiment. After background ...subtraction we observe 15 344 charm dimuon events, providing the largest sample currently available. The analysis exploits the large inclusive charged current sample – about 9×106 events after all analysis cuts – and the high resolution NOMAD detector to constrain the total systematic uncertainty on the ratio of charm dimuon to inclusive Charged Current (CC) cross-sections to ∼2%. We also perform a fit to the NOMAD data to extract the charm production parameters and the strange quark sea content of the nucleon within the NLO QCD approximation. We obtain a value of mc(mc)=1.159±0.075 GeV/c2 for the running mass of the charm quark in the MS¯ scheme and a strange quark sea suppression factor of κs=0.591±0.019 at Q2=20 GeV2/c2.
We have studied the muon neutrino and antineutrino quasi-elastic (QEL) scattering reactions (
ν
μ
n
→
μ
−
p
and
) using a set of experimental data collected by the NOMAD Collaboration. We have ...performed measurements of the cross-section of these processes on a nuclear target (mainly carbon) normalizing it to the total
ν
μ
(
) charged-current cross section. The results for the flux-averaged QEL cross sections in the (anti)neutrino energy interval 3–100 GeV are
and
for neutrino and antineutrino, respectively. The axial mass parameter
M
A
was extracted from the measured quasi-elastic neutrino cross section. The corresponding result is
M
A
=1.05±0.02(stat)±0.06(syst) GeV. It is consistent with the axial mass values recalculated from the antineutrino cross section and extracted from the pure
Q
2
shape analysis of the high purity sample of
ν
μ
quasi-elastic 2-track events, but has smaller systematic error and should be quoted as the main result of this work. Our measured
M
A
is found to be in good agreement with the world average value obtained in previous deuterium filled bubble chamber experiments. The NOMAD measurement of
M
A
is lower than those recently published by K2K and MiniBooNE Collaborations. However, within the large errors quoted by these experiments on
M
A
, these results are compatible with the more precise NOMAD value.
We present a precision measurement of the top-quark mass using the full sample of Tevatron √s = 1.96 TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated ...luminosity of 8.7 fb(-1). Using a sample of tt¯ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the W boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with in situ calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, M(top)=172.85±0.71(stat)±0.85(syst) GeV/c(2).
We present a combination of searches for the standard model Higgs boson using the full CDF run II data set, which corresponds to an integrated luminosity of 9.45-10.0 fb super(-1) collected from ...radicals = 1.96 TeV pp collisions at the Fermilab Tevatron. The searches consider Higgs boson production from gluon-gluon fusion, vector-boson fusion, and associated production with either a W or Z boson or a tt pair. Depending on the production mode, Higgs boson decays to W super(+)W super(-), ZZ, bb, tau super(+)tau super(-), and gamma gamma are examined. We search for a Higgs boson with masses (m sub(H)) in the range 90-200 GeV /c super(2). In the absence of a signal, we expect based on combined search sensitivity to exclude at the 95% credibility level the mass regions 90 < m sub(H) < 94 GeV /c super(2), 96 < m sub(H) < 106 GeV /c super(2), and 153 < m sub(H) < 175 GeV /c super(2). The observed exclusion regions are 90 < m sub(H) < 102 GeV /c super(2) and 149 < m sub(H) < 172 GeV /c super(2). A moderate excess of signal-like events relative to the background expectation at the level of 2.0 standard deviations is present in the data for the m sub(H) = 125 GeV /c super(2) search hypothesis. We also present interpretations of the data within the context of a fermiophobic model and an alternative standard model incorporating a fourth generation of fermions. Finally, for the hypothesis of a new particle with mass 125 GeV /c super(2), we constrain the coupling strengths of the new particle to W super(+ or -) bosons, Z bosons, and fermions.
Web Proxy Auto Discovery for the WLCG Dykstra, D; Blomer, J; Blumenfeld, B ...
Journal of physics. Conference series,
10/2017, Letnik:
898, Številka:
5
Journal Article
Recenzirano
Odprti dostop
All four of the LHC experiments depend on web proxies (that is, squids) at each grid site to support software distribution by the CernVM FileSystem (CVMFS). CMS and ATLAS also use web proxies for ...conditions data distributed through the Frontier Distributed Database caching system. ATLAS & CMS each have their own methods for their grid jobs to find out which web proxies to use for Frontier at each site, and CVMFS has a third method. Those diverse methods limit usability and flexibility, particularly for opportunistic use cases, where an experiment's jobs are run at sites that do not primarily support that experiment. This paper describes a new Worldwide LHC Computing Grid (WLCG) system for discovering the addresses of web proxies. The system is based on an internet standard called Web Proxy Auto Discovery (WPAD). WPAD is in turn based on another standard called Proxy Auto Configuration (PAC). Both the Frontier and CVMFS clients support this standard. The input into the WLCG system comes from squids registered in the ATLAS Grid Information System (AGIS) and CMS SITECONF files, cross-checked with squids registered by sites in the Grid Configuration Database (GOCDB) and the OSG Information Management (OIM) system, and combined with some exceptions manually configured by people from ATLAS and CMS who operate WLCG Squid monitoring. WPAD servers at CERN respond to http requests from grid nodes all over the world with a PAC file that lists available web proxies, based on IP addresses matched from a database that contains the IP address ranges registered to organizations. Large grid sites are encouraged to supply their own WPAD web servers for more flexibility, to avoid being affected by short term long distance network outages, and to offload the WLCG WPAD servers at CERN. The CERN WPAD servers additionally support requests from jobs running at non-grid sites (particularly for LHC@Home) which they direct to the nearest publicly accessible web proxy servers. The responses to those requests are geographically ordered based on a separate database that maps IP addresses to longitude and latitude.
•A complex permeability based magneto-elastic model for magnetic material is proposed.•A frequency dependent tanh function derived from Maxwell’s equations is modified.•The model is quite amenable ...for numerical analyses and it reduces computational time.•Dynamic losses of magnetic materials as a function of stress can be predicted.
The presence of mechanical stress significantly affects the performance of electrical machines, particularly in terms of permeability and losses of core materials. A precise modeling of electrical machines requires to consider such magneto-elastic couplings. An efficient approach needs a constitutive model to predict magneto-elastic hysteretic characteristics and its implementation into numerical analyses. However, it is a challenging task for engineers and researchers due to computational time and convergence issues. This paper deals with an approach to model the magneto-elastic behavior of electrical steels using complex permeability. The complex permeability function is used in this work for the first time in the literature to model the effects of stress. The proposed model is quite amenable to numerical analyses and it reduces computational time significantly. Although, the proposed approach is applicable to steady state or cyclic fields and it considers only reversible effects of stress. It provides an alternative way to consider magneto-elastic coupled behavior in numerical analysis of electrical devices involving magnetic materials. Computed results are in good agreement with measured ones with a maximum error of 2.5% for different stress levels and frequencies.
This Letter reports a search for a narrow resonant state decaying into two W bosons and two b quarks where one W boson decays leptonically and the other decays into a quark-antiquark pair. The search ...is particularly sensitive to top-antitop resonant production. We use the full data sample of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.45 fb(-1). No evidence for resonant production is found, and upper limits on the production cross section times branching ratio for a narrow resonant state are extracted. Within a specific benchmark model, we exclude a Z' boson with mass, M(Z'), below 915 GeV/c(2) decaying into a top-antitop pair at the 95% credibility level assuming a Z' boson decay width of Γ(Z') = 0.012 M(Z'). This is the most sensitive search for a narrow qq-initiated tt resonance in the mass region below 750 GeV/c(2).
We present a search for neutrino induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is ≃25 GeV. ...The search is motivated by an excess of electron-like events in the 200–475 MeV energy region as reported by the MiniBooNE experiment. In NOMAD, photons are identified via their conversion to e+e− in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino–nucleus interaction, or in a neutrino–nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined in situ using control data samples prior to opening the ‘signal-box’. In the signal region, we observe 155 events with a predicted background of 129.2±8.5±3.3. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent π0 decay, the measurement yields an upper limit on single photon events, <4.0×10−4 per νμ charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe 78 events with a predicted background of 76.6±4.9±1.9 yielding a more stringent upper limit, <1.6×10−4 per νμ charged current event.
We present a study of exclusive neutral pion production in neutrino–nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44×106 ...muon-neutrino Charged Current interactions in the energy range 2.5⩽Eν⩽300 GeV. Neutrino events with only one visible π0 in the final state are expected to result from two Neutral Current processes: coherent π0 production, ν+A→ν+A+π0 and single π0 production in neutrino–nucleon scattering. The signature of coherent π0 production is an emergent π0 almost collinear with the incident neutrino while π0's produced in neutrino–nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent π0 production signal are measured using data themselves. Having determined the backgrounds, and using the Rein–Sehgal model for the coherent π0 production to compute the detection efficiency, we obtain 4630±522(stat)±426(syst) corrected coherent-π0 events with Eπ0⩾0.5 GeV. We measure σ(νA→νAπ0)=72.6±8.1(stat)±6.9(syst)×10−40 cm2/nucleus. This is the most precise measurement of the coherent π0 production to date.
The mass of the
boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last ...missing component of the model. After observation of the Higgs boson, a measurement of the
boson mass provides a stringent test of the model. We measure the
boson mass,
, using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera-electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million
boson candidates is used to obtain
, the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega-electron volts;
, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.
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